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CVE-2018-12556

21
FAUCET Score

CVE-2018-12556 is a medium-severity vulnerability affecting the yarnpkg website's install.sh script. It allows remote attackers to sign tampered Yarn release packages with their own arbitrary key because the signature verification routine does not properly pin to the legitimate Yarn release key. This flaw has a CVSS score of 5.9, indicating a network-based attack with high integrity impact, but requires high attack complexity. There is no evidence of active exploitation, public exploit code, or significant community discussion surrounding this CVE.

Impacted Technologies

VendorProductVersion(s)CPE
<= 2018-06-05CPE matchmatch criteria
cpe:2.3:a:yarnpkg:website:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.0

5.9MEDIUM

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
HIGH
Availability Impact
NONE
Exploitability Score
2.2
Impact Score
3.6
CvssVersion
3.0

Exploit Intelligence

EPSS Score
1.77%
Probability of exploitation in next 30 days
EPSS Percentile
75.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-24
Model: v2026.06.15
This CVE's current EPSS score of 0.0177 is in the 55th percentile among its peer group of 19,953 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.2 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Remediation records are not available for this CVE.

References

packetstormsecurity.com / files/152703/Johnny-You-Are-Fired.html
Third Party AdvisoryVDB Entry
seclists.org / fulldisclosure/2019/Apr/38
Mailing ListThird Party Advisory
github.com / RUB-NDS/Johnny-You-Are-Fired
Third Party Advisory
github.com / RUB-NDS/Johnny-You-Are-Fired/blob/master/paper/johnny-fired.pdf
Third Party Advisory
github.com / yarnpkg/website/commits/master
Third Party Advisory
openwall.com / lists/oss-security/2019/04/30/4
Mailing ListThird Party Advisory